Apparatus for checking electronic type current mutual inductor

Abstract

The invention discloses an electronic current transformer calibrating device. Two current sources respectively transmit current signals A1 and A2, wherein, the A1 is bigger than the A2 and has different frequency from the A2. A reference transformer senses the A1 and the A2 which is amplified by N folds simultaneously, and a tested transformer senses the A1. A merging unit transmits a synchronization pulse signal to the reference transformer, the tested transformer and an AD converter simultaneously, obtains digital quantities of current sampling values of the reference transformer and the tested transformer and the digital quantity of the voltage value at the two ends of a sampling resistor which is obtained by conversion with a reference AD converter at the falling edge of the synchronization pulse signal, and synthesizes the digital quantities into a data frame and sends the data frame to a control computer. The control computer compares the current signal which is obtained by sensing the A1 by the reference transformer with the current signal output by the tested transformer, calibrates the scale difference and the angular difference of the tested transformer, compares the current signal which is obtained by sensing NA2 by the reference transformer with the current signal which is obtained by converting the output voltage from the reference AD converter, and performs self calibration on the reference transformer.

Description

technical field [0001] The invention belongs to the field of power system automation and relates to a transformer calibration device. Background technique [0002] Current transformer (abbreviated as CT) is an important equipment for electric energy metering and relay protection in the power system. Its long-term stability, reliability and safety are closely related to the safe and stable operation of the power system. There are two main types of current transformers currently in use: one is electromagnetic current transformers, and the other is electronic current transformers. Electromagnetic current transformers are based on the principle of electromagnetic induction and have been widely used in power systems. However, they have shortcomings such as magnetic saturation, ferromagnetic resonance, small dynamic range, inability to measure DC, and difficulties in insulation design, which have been difficult to meet the needs of power system development. need. Electronic curr...

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Problems solved by technology

At present, the domestic electronic current transformer calibration device is mainly realized by the (1) method; in the (2) method, an electronic current transformer with high enough long-term accuracy is required, and it is difficult to obtain such equipment. No patents or literature reports

[0004] The transformer calibration device using the above method (1) can obtain high calibration accuracy, but there are still some deficiencies: first, there are still problems such as magnetic saturation and secondary open circuit danger; second, it cannot Calibrate the accuracy under the high-order harmonic current source; finally, the calibration accuracy is easily affected by the frequency fluctuation of the current source and high-order harmonics, which affects the calibration accuracy

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